System for Heating a Paving Screed

ABSTRACT

A system for controlling heating of a screed plate includes screed plate disposed along the paving material delivery path. A first temperature sensor is operative to monitor a screed plate temperature and a second temperature sensor along the paving material delivery path is operative to monitor an actual paving material temperature of a paving material being applied to a work surface. A controller is configured to determine an estimated paving material temperature adjacent the screed plate based upon the actual paving material temperature and operate a heater to maintain the screed plate temperature within a temperature variation range relative to the estimated paving material temperature.

TECHNICAL FIELD

This disclosure relates generally to paving machines and, moreparticularly, to a system and method for controlling a screed plateheating system.

BACKGROUND

Paving machines are generally used for laying a heated paving material,such as bituminous aggregate mixtures or asphalt, onto a roadbed andspreading the heated paving material to achieve a road with a uniform,smooth surface. After the heated asphalt is laid, it is compacted andcools so that the road becomes passable by vehicles.

The paving machines include a screed assembly for spreading the heatedmaterial. The screed assembly typically has one or more screed platesand these screed plates are heated to prevent the paving material fromadhering or sticking to the screed plate. However, if the temperature ofthe screed plates is too high, energy is wasted, and the screed plate issubjected to excessive wear and tear. Generally, the screed platesshould be heated to a temperature close to the temperature of the heatedasphalt material.

U.S. Pat. No. 6,981,820 discloses a system and method for automatedheating of screed plates of a paving system. The system includes anelectric heater that applies heat to the screed plate, eithercontinuously or intermittently, depending on ambient conditions, thetemperature of the paving material and the speed at which the pavingmachine is operating. For intermittent operation, the supply of power tothe heater can be either manual or automatic through a control systemand sensors that monitor the temperature of the screed plate.

The foregoing background discussion is intended solely to aid thereader. It is not intended to limit the innovations described herein,nor to limit or expand the prior art discussed. Thus, the foregoingdiscussion should not be taken to indicate that any particular elementof a prior system is unsuitable for use with the innovations describedherein, nor is it intended to indicate that any element is essential inimplementing the innovations described herein. The implementations andapplication of the innovations described herein are defined by theappended claims.

SUMMARY

In one aspect, a system for controlling heating of a screed plateincludes a paving material delivery path, a screed plate, a firsttemperature sensor, a second temperature a heater, and a controller. Thescreed plate is operably mounted on a mobile machine and disposed alongthe paving material delivery path. The first temperature sensor isassociated with the screed plate and is configured to generate firsttemperature signals indicative of a screed plate temperature. The secondtemperature sensor is disposed along the paving material delivery pathand is configured to generate second temperature signals indicative ofan actual paving material temperature of a paving material being appliedto a work surface. The heater is operatively associated with the screedplate and configured to heat the screed plate. The controller isconfigured to access a temperature variation range, receive the firsttemperature signals, and determine the screed plate temperature basedupon the first temperature signals. The controller is further configuredto receive the second temperature signals, determine the actual pavingmaterial temperature based upon the second temperature signals, anddetermine an estimated paving material temperature adjacent the screedplate based upon the actual paving material temperature. The controlleris still further configured to generate command signals to operate theheater to maintain the screed plate temperature within the temperaturevariation range relative to the estimated paving material temperature.

In another aspect, a method of controlling heating of a screed plateincludes providing a screed plate operably mounted on a mobile machineand disposed along a material delivery path, accessing a temperaturevariation range, receiving first temperature signals from a firsttemperature sensor associated with the screed plate with the firsttemperature signals being indicative of a screed plate temperature, anddetermining the screed plate temperature based upon the firsttemperature signals. The method further includes receiving secondtemperature signals from a second temperature sensor disposed along apaving material delivery path with the second temperature signals beingindicative of an actual paving material temperature of a paving materialbeing applied to a work surface, determining the actual paving materialtemperature based upon the second temperature signals, determining anestimated paving material temperature adjacent the screed plate basedupon the actual paving material temperature, and generating commandsignals to operate a heater associated with the screed plate andconfigured to heat the screed plate to maintain the screed platetemperature within the temperature variation range relative to theestimated paving material temperature.

In still another aspect, a paving machine includes a ground engagingdrive mechanism to propel the paving machine, a paving material deliverypath, and a screed assembly, including a screed plate, disposed alongthe paving material delivery path and configured for applying pavingmaterial to a work surface. A first temperature sensor is associatedwith the screed plate and is configured to generate first temperaturesignals indicative of a screed plate temperature. The second temperaturesensor is disposed along the paving material delivery path and isconfigured to generate second temperature signals indicative of anactual paving material temperature of a paving material being applied toa work surface. A heater is operatively associated with the screed plateand configured to heat the screed plate. A controller is configured toaccess a temperature variation range, receive the first temperaturesignals, and determine the screed plate temperature based upon the firsttemperature signals. The controller is further configured to receive thesecond temperature signals, determine the actual paving materialtemperature based upon the second temperature signals, and determine anestimated paving material temperature adjacent the screed plate basedupon the actual paving material temperature. The controller is stillfurther configured to generate command signals to operate the heater tomaintain the screed plate temperature within the temperature variationrange relative to the estimated paving material temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a schematic illustration of a paving machine performing apaving operation according to the disclosure;

FIG. 2 depicts a flowchart illustrating a screed heating process inconjunction with the paving operation of FIG. 1;

FIG. 3 depicts a schematic illustration of a work site at which a pavingmachine and a haul truck are performing a paving operation;

FIG. 4 depicts a schematic illustration of a wireless communicationssystem;

FIG. 5 depicts a flowchart illustrating a screed heating process inconjunction with the paving operation of FIG. 3;

FIG. 6 depicts a schematic illustration similar to FIG. 3 but furtherincluding a remixing transfer vehicle between the paving machine and thehaul truck; and

FIG. 7 depicts a schematic illustration of a plant at which pavingmaterial is produced.

DETAILED DESCRIPTION

Referring to FIG. 1, a paving machine 10 is depicted. Paving machine 10may include a body 12, a material receiving unit such as a hopper 13 forstoring paving material, such as asphalt, and a material applicationsystem including a screed assembly 14 for applying paving material 102in a conventional manner to a work surface such as a roadbed 101. Atransport mechanism such as a conveyor system 15 transfers pavingmaterial from the hopper 13 to an auger 16, which distributes the pavingmaterial laterally to the screed assembly 14. The hopper 13, conveyorsystem 15, auger 16, and screed assembly 14 may sequentially define apaving material delivery path 17 within or of the paving machine 10.

The screed assembly 14 may include a body 21 with one or more screedplates 22 disposed along the paving material delivery path 17 and aheating system 23 operatively associated with the screed plate andconfigured to heat the screed plate. The heating system 23 may operateto maintain the screed plate 22 at a desired operational temperature. Inone example, the operational temperature may be set at a temperaturebetween 110 and 160 degrees C. The heating system 23 includes at leastone heater 24 that may be powered in any desired manner such as byelectricity or gas.

In operation, the heater 24 may be cycled on and off to maintain thescreed plate 22 within a desired temperature variation range adjacent orabout the desired operational temperature rather than continuouslyheating the screed plate. In an example in which the desired screedplate temperature is 130 degrees C. and the temperature variation rangeis ±10 degrees C., the heating system 23 may turn on the heater 24 whenthe screed plate temperature is falls below 120 degrees C. and turn offthe heater when the screed plate temperature is greater than 140 degreesC.

A prime mover such as engine 25 may be operatively connected to a groundengaging drive mechanism such as tracks 26 to propel the machine. Anoperator station 27 may include a plurality of input devices 28 forcontrolling the paving machine 10 and one or more display devices 29 fordisplaying information relevant to the operation of the machine and apaving operation.

A paver control system indicated generally at 30 to indicate associationwith paving machine 10 may operate to control certain aspects of thepaving machine and also communicate information between the pavingmachine and other machines and systems remote from the paving machine.The paver control system 30 may include an electronic control module orpaver controller 31. The paver controller 31 may receive input signalsfrom systems associated with the paving machine 10. The paver controller31 may also receive input signals from systems outside of the pavingmachine 10 such as GPS signals and signals indicative of the weatherthat may affect the operation of the paving machine 10 or the pavingprocess. The paver controller 31 may control the operation of variousaspects of the paving machine 10 as well as generate desiredcommunications, as described in more detail below.

The paver controller 31 may be an electronic controller that operates ina logical fashion to perform operations, execute control algorithms,store and retrieve data and other desired operations. The pavercontroller 31 may include or access memory, secondary storage devices,processors, and any other components for running an application. Thememory and secondary storage devices may be in the form of read-onlymemory (ROM) or random access memory (RAM) or integrated circuitry thatis accessible by the controller. Various other circuits may beassociated with the paver controller 31 such as power supply circuitry,signal conditioning circuitry, driver circuitry, and other types ofcircuitry.

The paver controller 31 may be a single controller or may include morethan one controller disposed to control various functions and/orfeatures of the paving machine 10. The term “controller” is meant to beused in its broadest sense to include one or more controllers and/ormicroprocessors that may be associated with the paving machine 10 andthat may cooperate in controlling various functions and operations ofthe machine 10. The functionality of the paver controller 31 may beimplemented in hardware and/or software without regard to thefunctionality. The paver controller 31 may rely on one or more data mapsrelating to the operating conditions and the operating environment ofthe paving machine 10 that may be stored in the memory of controller.Each of these data maps may include a collection of data in the form oftables, graphs, and/or equations to maximize the performance andefficiency of the paving machine 10 and its operation.

The paver control system 30 and the paver controller 31 may be locatedon the paving machine 10 or may be distributed so that certain functionsare performed on the paving machine 10 and other functions are performedremotely.

Paving machine 10 may be equipped with a plurality of paver sensors 35,as shown generally by an arrow in FIG. 1 indicating association with thepaving machine, that provide data indicative (directly or indirectly) ofvarious operating parameters of the paving machine, systems associatedwith the paving machine, and/or the operating environment in which thepaving machine is operating. The term “sensor” is meant to be used inits broadest sense to include one or more sensors and related componentsthat may cooperate to sense various functions, operations, and operatingcharacteristics of a machine or system and/or aspects of the environmentin which the machine or system is operating. In operation, a sensor maygenerate signals indicative of a characteristic or data being measured.

A position sensing system 36, as shown generally by an arrow in FIG. 1indicating association with the paving machine 10, may include aposition sensor 37, also shown generally by an arrow in FIG. 1, to sensethe position of the paving machine. The position sensor 37 may include aplurality of individual sensors that cooperate to generate and provideposition signals to paver controller 31 indicative of the position andorientation of the machine 10. The position sensor 37 may include one ormore sensors that interact with a positioning system such as a globalnavigation satellite system or a global positioning system to operate asa position sensor. The paver controller 31 may use position signals fromthe position sensor 37 to determine the position of the paving machine10 relative to an earth reference (e.g., GPS).

A ground speed sensor 38 for determining the ground speed of the pavingmachine 10 may be provided as a dedicated or standalone sensor or aspart of position sensor 37. Alternatively, if desired, the positionsensing system 36 may also be used to determine the ground speed of thepaving machine 10.

Additional sensors may be provided such as a mix delivery or feed ratesensor 40 that may be used to determine the rate at which material fromthe hopper 13 is being fed by the conveyor system 15 to the screedassembly 14. A first or screed plate temperature sensor 41 may beassociated with, such as disposed adjacent, the screed plate 22 todetermine or monitor the temperature of the screed plate. A second ordelivery path temperature sensor 42 may be provided at any locationalong the paving material delivery path 17 of the paving machine 10. Inone example, the delivery path temperature sensor 42 may be provided ordisposed at a location remote from the screed plate 22 such as within oralong the hopper 13. In another example, the delivery path temperaturesensor 42 may be disposed along the conveyor system 15. In a furtherexample, the delivery path temperature sensor 42 may be disposedadjacent the screed assembly 14 such as adjacent the auger 16.

The delivery path temperature sensor 42 may be used to determine ormonitor the temperature of the paving material along the paving materialdelivery path 17 adjacent the sensor to assist in controlling thetemperature of the screed plate 22 as discussed in further detail below.Thus, it may be understood that the screed plate temperature sensor 41generates first or screed plate temperature signals indicative of thetemperature of the screed plate 22 and the delivery path temperaturesensor 42 generates second or delivery path temperature signalsindicative of the temperature at the location of the delivery pathtemperature sensor.

If desired, an ambient weather sensor 43 may be provided on pavingmachine 10. In an alternate embodiment, weather conditions at the pavingmachine 10 may be accessed by the paver controller 31 from various knownsources.

During a paving operation, it may be desirable to maintain thetemperature of the screed plate 22 at or above the temperature of thepaving material to prevent or reduce the likelihood of that pavingmaterial will adhere or stick to the screed plate. Accordingly, it maybe desirable to determine or estimate the temperature of the pavingmaterial adjacent the screed plate 22 and control the heating system 23to maintain the screed plate at a desired temperature or within adesired temperature variation range. In one example, the desiredtemperature variation range may be set at the temperature of the pavingmaterial at the screed plate 22 ±5 degrees C. In another example, thetemperature variation range may be set at the temperature of the pavingmaterial at the screed plate 22 ±10 degrees C. In still other examples,the temperature variation range of the screed plate 22 may be set sothat the lower limit is at the estimated temperature of the pavingmaterial at the screed plate. Other temperature ranges are contemplated.

To determine or estimate the temperature of the paving material adjacentthe screed plate 22, the temperature of the paving material adjacent thedelivery path temperature sensor 42 may be determined and adjustmentsmade, if desired, to the measured or sensed temperature based uponvarious factors or temperature adjustment characteristics. Onetemperature adjustment characteristic may be the distance between thedelivery path temperature sensor and the screed plate 22. For example,if the delivery path temperature sensor 42 is adjacent the auger 16, asmall or no adjustment in the sensed temperature may be necessary toestimate the temperature of the paving material adjacent the screedplate 22. If the delivery path temperature sensor 42 is further remotefrom the screed plate 22, such as at hopper 13, a greater adjustment tothe sensed temperature may be necessary to estimate the temperature ofthe paving material adjacent the screed plate 22.

In some instances, greater accuracy of the estimate of the temperatureof the paving material adjacent the screed plate 22 may be achieved byutilizing additional or other temperature adjustment characteristicssuch as the weather conditions at the paving machine 10 (e.g., theambient temperature of the air) and/or the rate at which the pavingmaterial is being fed from the hopper 13 to the screed assembly 15.

Referring to FIG. 2, a flowchart of an exemplary paving operationutilizing paving machine 10 is depicted. At stage 150, a desiredtemperature variation range that the screed plate temperature can varyduring a paving operation may be set or stored within paver controller31. In an alternate embodiment, the temperature variation range may bestored remotely from the paver controller 31 and the paver controllermay access the desired temperature range. The temperature variationrange may reflect a range of acceptable or desirable screed temperaturesfor a given paving operation. In other words, the temperature variationrange represents a range of temperatures of the screed plate 22 withinor between which the heating system 23 will maintain the temperature ofthe screed plate based upon an estimate of the temperature of the pavingmaterial at the screed plate.

A temperature adjustment based upon the distance between the screedplate 22 and the delivery path temperature sensor 42 may be set orstored within the paver controller 31 at stage 151. In an alternateembodiment, such a distance temperature adjustment may be storedremotely from the paver controller 31 and the paver controller mayaccess the distance temperature adjustment. The distance temperatureadjustment may be used by the paver controller 31 to assist inestimating the paving material temperature adjacent the screed plate 22based upon the temperature at the delivery path temperature sensor 42.Since the distance between the screed plate 22 and the delivery pathtemperature sensor 42 may be fixed for most paving equipment setups,such an adjustment characteristic may be referred to as a fixedtemperature adjustment characteristic for a given paving machine setup.

At stage 152, a dynamic temperature adjustment characteristic such asthe weather conditions (e.g., ambient temperature and/or windconditions) at the paving machine 10 may be determined. The weatherconditions may be determined by an on-board sensor such as ambientweather sensor 43 or may be accessed by the paver controller 31 fromknown weather sources. Still another dynamic temperature adjustmentcharacteristic in the form of the feed rate of paving material from thehopper 13 to the screed assembly 14 may be determined at stage 153 basedupon feed rate signals or data from the feed rate sensor 40.

At stage 154, the paver controller 31 may determine the actual pavingmaterial temperature at the delivery path temperature sensor 42 basedupon signals from the sensor. The paver controller 31 may determine atstage 155 an estimated paving material temperature adjacent the screedplate 22. In doing so, the paver controller 31 may utilize the sensed oractual paving material temperature at the delivery path temperaturesensor 42 and adjust the sensed temperature based upon one or moretemperature adjustment characteristics. In one example, the pavercontroller 31 may utilize lookup charts or equations to determine anestimate of the temperature drop from the delivery path temperaturesensor 42 to the screed plate 22 based upon the distance from thedelivery path temperature sensor to the screed plate in view of theweather conditions and the feed rate of the paving material.

For example, one would expect a greater temperature drop if the deliverypath temperature sensor 42 is relatively far from the screed plate 22,the paving operation is occurring on a relatively cool and windy day,and the paving material is being fed relatively slowly. The estimatedtemperature drop would be expected to be less as the distance betweenthe delivery path temperature sensor 42 and the screed plate 22 isreduced, as the ambient temperature at the paving machine 10 increases,and as the feed rate of paving material increases. In an extremeexample, if the delivery path temperature sensor 42 were positionedadjacent the auger 16, little or no temperature adjustment of the sensedtemperature may be necessary to estimate the temperature of the pavingmaterial at the screed plate 22.

At stage 156, the paver controller 31 may determine the screed platetemperature at the screed plate temperature sensor 41 based upon screedplate temperature signals from the sensor. The paver controller 31 maygenerate at stage 157 command signals to maintain the temperature of thescreed plate 22 within the desired temperature range of the estimate ofthe paving material temperature at the screed plate. In doing so, thepaver controller 31 may compare the actual temperature of the screedplate 22 to the estimated temperature of the paving material at thescreed plate and turn on or cycle the heating system 23 as necessary sothat the temperature of the screed plate remains within the desiredtemperature variation range of the estimated temperature of the pavingmaterial at or adjacent the screed plate.

In addition to controlling the heating system 23 by cycling the heater24 on and off to heat the screed plate 22, the paver controller 31 maybe configured to turn off the heater for an extended period of time ifthe screed is substantially hotter (i.e., above the desired temperaturerange) than the estimated temperature of the paving material at thescreed plate. Further, the paver controller 31 may be configured tooperate the heater for an extended period of time if the screed issubstantially cooler (i.e., below the desired temperature range) thanthe estimated temperature of the paving material at the screed plate.Relatively large differences between the estimate of the paving materialtemperature at the screed plate 22 as compared to the actual temperatureof the screed may occur upon a change in the source of the pavingmaterial (e.g., upon a new load of paving material being dumped intohopper 13).

At stage 158, the paving machine 10 may continue to be operated andpaving material 102 applied to the work surface and stages 152-157repeated.

In some instances, the delivery path temperature sensor may not belocated on the paving machine 10. In such case, a sensed or actualpaving material temperature remote from the paving machine 10 may bedetermined and the remote actual paving material temperature used toestimate the temperature of the paving material adjacent the screedplate 22.

In one example, a paving machine 10 may be operated in conjunction withmaterial supply machine such as a haul truck 50 that transports andsupplies paving material to the paving machine. Referring to FIG. 3,haul truck 50 may include a chassis 51 that supports a prime mover suchas an engine 52 and a cab 53 for an operator. The engine 52 isoperatively connected to and drives a ground engaging drive mechanismsuch as wheels 54. A material transport unit such as a dump body 55 ispivotally mounted on the chassis 51 and receives a payload to be hauledfrom one location to another.

Haul truck 50 may include a truck control system 56 and a truckcontroller 57, each being generally indicated by an arrow in FIG. 3indicating association with the haul truck 50, that are generallysimilar or identical to the paver control system 30 and the pavercontroller 31 of the paving machine 10, respectively. The truck controlsystem 56 and the truck controller 57 may be located on the haul truck50 or may be distributed so that certain functions are performed on thehaul truck 50 and other functions are performed remotely.

Haul truck 50 may be equipped with a plurality of truck sensors 58, asshown generally by an arrow in FIG. 3 indicating association with thehaul truck, that provide data indicative (directly or indirectly) ofvarious operating parameters of the truck, systems associated with thetruck, and/or the operating environment in which the truck is operating.

A position sensing system 59, as shown generally by an arrow in FIG. 3indicating association with the haul truck 50, may include a positionsensor 60, also shown generally by an arrow in FIG. 3, to sense theposition of the truck. The position sensing system 59 and positionsensor 60 may be generally similar to the position sensing system 36 andposition sensor 37 of paving machine 10, respectively. Further, the haultruck 50 may include a ground speed sensor 61 for determining the groundspeed of the haul truck, with the ground speed sensor being generallysimilar to that of the paving machine 10.

Haul truck 50 may also include truck temperature sensor 62 and a pivotposition sensor 63. The truck temperature sensor 62 may be positioned atany desired location relative to the dump body 55 so as to monitor thetemperature of the load (e.g., paving material) within the dump body 55.Accordingly, the truck temperature sensor 62 functions as a deliverypath temperature sensor that is remote from the paving machine 10. Thepivot position sensor 63 may be used to monitor the position of the dumpbody relative to the chassis 51 to control the flow of material from thedump body.

Each of the paving machine 10 and haul truck 50 may include a wirelesscommunications system 65 to permit wireless transmission of a pluralityof instructions and information between the paving machine 10 and thehaul truck 50 as well as permit communication with other machines andsystems remote from the paving machine and haul truck. In one embodimentdepicted in FIG. 4, each wireless communications system 65 may include atransmitter 66 for transmitting signals and a receiver 67 for receivingsignals from a transmitter system of another wireless communicationssystem. In some instances, the transmitter 66 and the receiver 67 may becombined as a transceiver system. In some embodiments, the pavingmachine 10 may only include a receiver system and the haul truck 50 mayonly include a transmitter system.

Wireless communications systems 65 may implement or utilize any desiredsystem or protocol including any of a plurality of communicationsstandards. The desired protocols will permit communication between thepaving machine 10 and haul truck 50 as well as any other desiredmachines or systems. Examples of wireless communications systems orprotocols that may be used by the wireless communications systems 65include a wireless personal area network such as Bluetooth® (e.g., IEEE802.15), a local area network such as IEEE 802.11b or 802.11g, acellular network, or any other system or protocol for data transfer.Other wireless communications systems and configurations arecontemplated.

As depicted in FIG. 3, during a paving operation, the paving machine 10may be supplied with paving material from an aligned haul truck 50 and alayer of paving material 102 applied to the work surface. In someinstances, the paving machine 10 may push the haul truck 50 while thepaving machine is simultaneously applying a layer of paving material andthe haul truck is loading paving material into the hopper 13 of thepaving machine.

If the paving machine 10 does not include a delivery path temperaturesensor 42, a remote (relative to the paving machined 10) sensor in theform of the truck temperature sensor 62 on the haul truck 50 may be usedto determine the temperature of the paving material within the dump body55. In such case, a paving material delivery path may be defined by thedump body 55 of the haul truck 50 together with the paving materialdelivery path 17 within or of the paving machine 10. With such aconfiguration, the control of the operation of the heating system 23 ofthe paving machine 10 may be similar to that depicted in FIG. 1.

As described in more detail below, one difference between the operationof FIGS. 1 and 3 is that the temperature of the paving material alongthe material delivery path is sensed at the dump body 55 of the haultruck 50 rather than at a location on the paving machine 10. Anotherdifference is that the paver controller 31 may operate in conjunctionwith the truck controller 57 with the functionality of controlling theheating system 23 distributed between the paver controller and the truckcontroller in any desired manner. As used herein, the paver controller31, the truck controller 57 or a combination of the two controllers maybe referred to herein and is depicted generally in FIG. 3 as controller65.

Referring to FIG. 5, a flowchart of an exemplary paving operationutilizing paving machine 10 in conjunction with haul truck 50 isdepicted. Descriptions of stages that are identical or similar to stagesof FIG. 2 are, in some instances, shortened for purposes of brevity.

At stage 160, a desired temperature variation range that the screedplate temperature can vary may be set or stored within the controller65. In an alternate embodiment, the variation temperature range may bestored remotely from the controller 65 and the controller may access thedesired temperature range.

A temperature adjustment based upon the distance between the screedplate 22 and the delivery path temperature sensor (e.g., trucktemperature sensor 62) may be set or stored within the paver controller31 at stage 151. In an alternate embodiment, such a distance temperatureadjustment may be stored remotely from the controller 65 and thecontroller may access the distance temperature adjustment.

At stage 162, the weather conditions (e.g., ambient temperature and/orwind conditions) at the paving machine 10 and haul truck 50 may bedetermined. The weather conditions may be determined by an on-boardsensor such as ambient weather sensor 43 or may be accessed by thecontroller 65 from known weather sources. The feed rate of pavingmaterial from the haul truck 50 to the hopper 13 and to the screedassembly 14 may be determined at stage 163 based upon signals or datafrom the feed rate sensor 40 on the paving machine 10 and the positionof the dump body 55 based upon signals or data from the pivot positionsensor 63.

At stage 164, the controller 65 may determine the actual paving materialtemperature at truck temperature sensor 62 of the haul truck 50 basedupon truck temperature signals from the sensor.

In one example, the actual temperature of the paving material within thedump body 55 may be determined by the truck controller 57 based uponsignals or data from the truck temperature sensor 62 associated with thedump body. The actual temperature of the paving material within the dumpbody 55 may be transmitted at stage 165 by the truck controller 57 viathe transmitter 66 of the wireless communications systems 65 of the haultruck 50 to the receiver 67 of the wireless communications system 65 ofthe paving machine 10.

In another example, signals or data from the truck temperature sensor 62may be transmitted by the truck controller 57 via the transmitter 66 ofthe wireless communications systems 65 of the haul truck 50 to thereceiver 67 of the wireless communications system 65 of the pavingmachine 10 and the paver controller 31 may determine the actualtemperature of the paving material within the dump body 55 based uponthe transmitted signals or data from the truck temperature sensor 62.

The controller 65 (e.g., paver controller 31) may determine at stage 166an estimated temperature of the paving material adjacent the screedplate 22. In doing so, the controller 65 may utilize the actual pavingmaterial temperature at the truck temperature sensor 62 (which functionsas a remote delivery path temperature sensor) and adjust the actualtemperature based upon any of the temperature adjustmentcharacteristics.

At stage 167, the controller 65 may determine the actual screed platetemperature at the screed plate temperature sensor 41 based upon screedplate signals from the sensor. The controller 65 may generate at stage168 command signals to maintain the temperature of the screed plate 22within the temperature variation range of the estimated paving materialtemperature at or adjacent the screed plate. In doing so, the controller65 may compare the actual temperature of the screed plate 22 to theestimated temperature of the paving material at the screed plate andturn on or cycle the heating system 23 as necessary so that thetemperature of the screed plate remains within the desired temperaturerange of the estimated temperature of the paving material.

At stage 169, the paving machine 10 and haul truck 50 may continue to beoperated and paving material 102 applied to the work surface and stages162-168 repeated.

In another example in which the delivery path temperature sensor islocated on a material supply machine, the paving machine 10, the pavingmachine may be operated in conjunction with a remixing transfer vehicle70, either with (FIG. 6) or without a haul truck 50. Remixing transfervehicle 70 permits material that has been segregated by size and/ortemperature to be remixed before being fed into the hopper 13 of thepaving machine 10. Remixing transfer vehicle 70 includes a materialtransfer and remix system 71 and a prime mover such as an engine 72operatively connected to a ground engaging drive mechanism such aswheels 73.

The material transfer and remix system 71 may include a dump hopper 74into which paving material may be dumped and a conveyor 75 for conveyingor transporting material from the dump hopper to a remix hopper 76 inwhich the paving material may be remixed and re-heated. The remixingtransfer vehicle 70 may further include a swingable or pivotabletransfer conveyor 77 for conveying or transporting material from theremix hopper 76 to an outlet 78. By aligning outlet 78 with hopper 13 ofpaving machine 10, material exiting from the outlet may be conveyed fromthe dump hopper 74 to the hopper 13 of the paving machine after theremixing operation has been completed.

Remixing transfer vehicle 70 may include a vehicle control system 80 anda vehicle controller 81 generally similar or identical to the pavercontrol system 30 and the paver controller 31 of paving machine 10,respectively. The remixing transfer vehicle 70 may also include aplurality of vehicle sensors, generally indicated at 82, that aregenerally similar or identical to the paver sensors 35 of the pavingmachine 10 and/or the truck sensors 58 of the haul truck 50. One exampleof a vehicle sensor may be a remix temperature sensor 84 that may beprovided or disposed at the remix hopper 76, along the pivotabletransfer conveyor 77 or at any other desired location. The remixtemperature sensor 84 may function as a delivery path temperature sensorthat is remote from the paving machine 10.

The remixing transfer vehicle 70 may also include a wirelesscommunications system generally indicated at 65 that is generallysimilar or identical to the wireless communications systems 65 of thepaving machine 10 and the haul truck 50.

Operation of the paving machine 10 with remixing transfer vehicle 70 maybe substantially identical to the operation of the paving machine withthe haul truck 50 and the description thereof is not repeated herein. Insuch case, the remix temperature sensor 84 may operate as the remotedelivery path temperature sensor.

In still other examples, the delivery path temperature sensor may bedisposed at a location farther remote from the paving machine 10. Forexample, the haul truck 50 may provide temperature data to the pavingmachine 10 before the haul truck has arrived at the paving site. Inanother example, the delivery path temperature sensor may be located ata plant 110 configured to produce a paving material such as asphalt asdepicted in FIG. 7.

Plant 110 may produce paving material such as asphalt from bitumen,aggregate, and other materials or fillers. The paving material is oftenproduced in batches with each batch stored or held in a separate storageor holding location such as a silo until it is loaded into a haul truck50 at a loading station. Each holding location may be dedicated tostoring or holding paving material for a particular paving site andpaving material within a particular holding location is periodicallyloaded into a haul truck for transport to the paving site. Thecharacteristics of each batch stored within a holding location may beset based upon the desired characteristics for a particular paving job.For example, the amount of oil, the size of the aggregate, and thetemperature may be set based upon the desired characteristics of thepaving material and the requirements of each paving job.

Each batch may be periodically or continuously mixed at the holdinglocation and maintained at a desired temperature. The temperature atwhich the paving material is maintained may be set based upon a desiredtemperature at which the paving material will be loaded into a haultruck 50. Such loading temperature may be based upon the desiredtemperature at which the load will be delivered to the paving machine10, the ambient temperature of the air, the expected time required forthe haul truck 50 to drive from the plant 110 to the paving machine 10as well as any expected or anticipated waiting time for the truck at thepaving site.

Plant 110 may include a plant control system 111 and a plant controller112 generally similar or identical to the paver control system 30 andthe paver controller 31 of the paving machine 10, respectively. Plant110 may also include a plurality of plant sensors indicated generally at113 such as batch temperature sensor indicated generally at 114operative to monitor the temperature of the batch of paving materialwithin each holding location. The batch temperature sensor 114 mayfunction as a delivery path temperature sensor that is remote from thepaving machine 10.

Operation of the paving machine 10 with the batch temperature sensor 114functioning as the remote delivery path temperature sensor may besubstantially identical to the operation of the paving machine with thehaul truck 50 and the description thereof is not repeated herein. Itwill be appreciated that the estimation of the paving materialtemperature may be more complex due to the distance between the pavingmachine 10 and the plant 110.

INDUSTRIAL APPLICABILITY

The industrial applicability of the system described herein will bereadily appreciated from the forgoing discussion. The foregoingdiscussion is applicable to systems used with paving machines 10 to heatthe screed plate 22 within a desired temperature range of the pavingmaterial at the screed plate during a paving operation. The pavingoperation may be used at a construction site, a roadwork site, a parkinglot, or any other area in which the application of paving material to awork surface is desired.

The foregoing system estimates the temperature of the paving materialadjacent the screed plate 22 and maintains the screed plate at atemperature within a predetermined range from the estimated temperature.The estimated temperature may be based upon a delivery path temperaturesensor disposed along the delivery path of the paving material to thescreed assembly 14. In some instances, the delivery path temperaturesensor 42 may be disposed on the paving machine 10. In other instances,the delivery path temperature sensor may be disposed on a movablemachine that supplies paving material to the paving machine 10 such as ahaul truck 50 or a remixing transfer vehicle 70. In still otherinstances, the delivery path temperature sensor may be located at aplant 110 at which the paving material is mixed.

By maintaining the temperature of the screed plate 22 within apredetermined temperature range of the estimated temperature of thepaving material at the screed plate 22, certain benefits may beachieved. The heating system may use less energy to heat the screedplate 22 since the screed plate is only heated when necessary. Inaddition, by only heating the screed plate 22 when necessary, theheaters 24 are subject to less wear and tear, thus increasing thelifespan of the heaters.

It will be appreciated that the foregoing description provides examplesof the disclosed system and technique. However, it is contemplated thatother implementations of the disclosure may differ in detail from theforegoing examples. All references to the disclosure or examples thereofare intended to reference the particular example being discussed at thatpoint and are not intended to imply any limitation as to the scope ofthe disclosure more generally. All language of distinction anddisparagement with respect to certain features is intended to indicate alack of preference for those features, but not to exclude such from thescope of the disclosure entirely unless otherwise indicated.

Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context.

Accordingly, this disclosure includes all modifications and equivalentsof the subject matter recited in the claims appended hereto as permittedby applicable law. Moreover, any combination of the above-describedelements in all possible variations thereof is encompassed by thedisclosure unless otherwise indicated herein or otherwise clearlycontradicted by context.

1. A system for controlling heating of a screed plate, comprising: apaving material delivery path; a screed plate operably mounted on amobile machine and disposed along the paving material delivery path; afirst temperature sensor associated with the screed plate, the firsttemperature sensor being configured to generate first temperaturesignals indicative of a screed plate temperature; a second temperaturesensor disposed within a hopper of the mobile machine, the secondtemperature sensor being configured to generate second temperaturesignals indicative of an actual paving material temperature of a pavingmaterial being applied to a work surface; a heater operativelyassociated with the screed plate and configured to heat the screedplate; and a controller configured to: access a temperature variationrange; receive the first temperature signals; determine the screed platetemperature based upon the first temperature signals; receive the secondtemperature signals; determine the actual paving material temperaturebased upon the second temperature signals; determine an estimated pavingmaterial temperature adjacent the screed plate based upon the actualpaving material temperature, at least one temperature adjustmentcharacteristic associated with a location of the second temperaturesensor, and a feed rate of the paving material; and generate commandsignals to operate the heater to maintain the screed plate temperaturewithin the temperature variation range relative to the estimated pavingmaterial temperature.
 2. (canceled)
 3. The system of claim 1, whereinthe feed rate of the paving material is determined based upon feed ratesignals received at the controller from a feed rate sensor positioned onthe mobile machine and position signals received at the controller froma material transport unit.
 4. The system of claim 1, wherein theestimated paving material temperature is further based upon weatherconditions at the mobile machine.
 5. (canceled)
 6. The system of claim1, wherein the mobile machine further comprises a transport mechanism totransport paving material between the hopper and the screed plate. 7.(canceled)
 8. The system of claim 6, wherein a feed rate sensor isdisposed adjacent the transport mechanism and configured to generatefeed rate signals indicative of the feed rate of the paving material,and wherein the controller is configured to determine the feed ratebased on the feed rate signals.
 9. (canceled)
 10. (canceled) 11.(canceled)
 12. A method of controlling heating of a screed plate,comprising: providing a screed plate operably mounted on a mobilemachine and disposed along a material delivery path; receiving firsttemperature signals from a first temperature sensor associated with thescreed plate, the first temperature signals being indicative of a screedplate temperature; determining the screed plate temperature based uponthe first temperature signals; receiving second temperature signals froma second temperature sensor disposed along a paving material deliverypath, the second temperature signals being indicative of an actualpaving material temperature of a paving material being applied to a worksurface; determining the actual paving material temperature based uponthe second temperature signals; determining an estimated paving materialtemperature adjacent the screed plate based upon the actual pavingmaterial temperature; setting a temperature variation range based on theestimated paving material temperature; and generating command signals tooperate a heater associated with the screed plate and configured to heatthe screed plate to maintain the screed plate temperature within thetemperature variation range.
 13. The method of claim 12, furtherincluding determining the estimated paving material temperature basedupon at least one temperature adjustment characteristic associated witha location of the second temperature sensor.
 14. The method of claim 13,further including determining the estimated paving material temperaturebased upon a feed rate of the paving material.
 15. The method of claim13, further including determining the estimated paving materialtemperature based upon weather conditions at the mobile machine.
 16. Themethod of claim 12, further comprising transmitting the signalsindicative of the actual paving material temperature from a secondwireless communications system on a material supply machine to a firstwireless communications system on the mobile machine.
 17. A pavingmachine comprising: a ground engaging drive mechanism to propel thepaving machine; a paving material delivery path; a screed assemblydisposed along the paving material delivery path and configured forapplying paving material to a work surface, the screed assemblyincluding a screed plate; a first temperature sensor associated with thescreed plate, the first temperature sensor being configured to generatefirst temperature signals indicative of a screed plate temperature; asecond temperature sensor disposed within a hopper of the pavingmachine, the second temperature sensor being configured to generatesecond temperature signals indicative of an actual paving materialtemperature of a paving material being applied to a work surface; aheater operatively associated with the screed plate and configured toheat the screed plate; and a controller configured to: access atemperature variation range; receive the first temperature signals;determine the screed plate temperature based upon the first temperaturesignals; receive the second temperature signals; determine the actualpaving material temperature based upon the second temperature signals;determine an estimated paving material temperature adjacent the screedplate based upon the actual paving material temperature, at least onetemperature adjustment characteristic associated with a location of thesecond temperature sensor, a feed rate of the paving material, andweather conditions at the paving machine; and generate command signalsto operate the heater to maintain the screed plate temperature withinthe temperature variation range relative to the estimated pavingmaterial temperature. 18-20. (canceled)
 21. The system of claim 1,wherein the first temperature sensor is positioned adjacent the screedplate.
 22. The system of claim 1, wherein the temperature variationrange is the estimated paving material temperature ±10 degrees C. 23.The method of claim 12, wherein the method is repeated.
 24. The methodof claim 14, wherein the second temperature sensor is disposed in ahopper of the mobile machine.
 25. The method of claim 14, furtherincluding determining the feed rate based upon feed rate signals from afeed rate sensor disposed adjacent to a transport mechanism of themobile machine.
 26. The method of claim 25, wherein the feed rate isfurther determined based in part on position signals from a positionsensor disposed on a material supply machine.
 27. The method of claim26, wherein the estimated paving material temperature is furtherdetermined based in part on weather conditions at the mobile machine.28. The paving machine of claim 17, wherein the at least one temperatureadjustment characteristic associated with a location of the secondtemperature sensor is a fixed temperature adjustment characteristic. 29.The paving machine of claim 17, wherein the controller is configured tocycle the heater on and off to heat the screed plate.